The Aleo maintainers are excited to announce a new version of the Aleo Stack. This update includes changes to the node implementation snarkOS and the high-level programming language Leo - as well as their supporting libraries.

This release is one of the largest and most significant upgrades to Aleo since the launch of Mainnet. It introduces three major capabilities:

• Leo v4.0.0: a complete overhaul of the Leo language, unifying five function-like constructs into a single fn keyword with explicit execution context modifiers.
• Interfaces and Dynamic Dispatch: compile-time program contracts and runtime function resolution, enabling standardized interfaces, pluggable architectures, and open composability.
• Onchain SNARK Verification: new snark.verify and snark.verify.batch opcodes that allow programs to verify Varuna proofs directly onchain.

If you want to try it out, you can build from source today or download the mainnet release from Github March 30th. Find the current release schedule at:https://aleo.org/roadmap.

Improvements for Node Operators

Automated Ledger Checkpoints: A new --auto-db-checkpoints=<path> flag enables rolling RocksDB checkpoint-based ledger backups every 1,000 blocks, maintaining up to 5 rolling snapshots.

Filesystem Reorganization: Node-specific data (peer lists, proposal cache) now lives in a dedicated node-data directory, separate from the ledger. Use --node-data for custom paths and --auto-migrate-node-data for automatic migration.

Dynamic Validator Whitelist: Nodes now maintain a file listing all currently connected validators, updated with every heartbeat. The format is IP-port pairs for easy scripting and firewall integration.

New Metrics: Build info (version, git commit, branch) is now exposed as Prometheus gauge metrics. New gauges track total connected validator stake and the combined stake of validators running the same snarkOS SHA, useful during rolling upgrades.

Network Stability: TCP socket configuration has been hardened, connection timeouts relaxed (handshake increased from 1s to 3s, high-level from 3s to 5s), and the BFT communication layer refactored from channel-based to direct callbacks, reducing async overhead and improving error propagation. CDN sync performance is improved through unchecked deserialization and threadpool reuse.

New REST Endpoints: New routes for historical staking rewards, connected validator queries (/{network}/connections/bft/…), and amendment deployment metadata (/program/{programID}/amendment_count).